The present invention relates to a machine for the single cycle manufacture of corrugated H-divider shipping containers. More specifically, the machine is particularly useful for manufacturing containers having an inside-outside Bliss-type corner construction.
H-divider and similar two-cell shipping containers made from corrugated paperboard are well known in the art. Containers of this type can be made in a number of different configurations. A common one is of Bliss-type construction in which the H-divider portion is integral with the end walls, or side walls, of the container. In Bliss-type construction a body blank is folded and assembled about separate end wall portions. Outside flaps integral with the body blank are glued to the end walls to form the container. The Bliss container is a pseudomorph of the slat-type wooden containers still occasionally used for shipping fruit and fresh produce. U.S. Pat. No. 3,679,505 to Wasyluka et al. is one example of a machine designed to produce a conventional Bliss box.
In some of its end wall configurations, Bliss-type containers may have improved top-to-bottom compression resistance, since the end wall flaps can serve as support columns. Top-to-bottom compression or crush resistance is particularly important where palletized containers, which may contain heavy interior contents, are stacked several tiers high in warehouses and during shipping. Improved top-to-bottom compression resistance is normally achieved by putting more fiber in the side and end walls of the container. This can be done by using a heavier basis weight board or by using multiple plies in the side and end walls. In many cases significant improvements in top-to-bottom compression resistance can be achieved by locating the multiple plies only in the corner areas of the container. The inside-outside Bliss container is an example. Here double plies are present in the corner areas along both end and side walls. On the end walls these are located outside of the container and along the side walls they are located inside the container. It should be noted that the terms sides and ends, as well as length and width, are relative in all of the description that follows. The term "end wall" is used to signify that side wall to which the outside body flaps are glued.
Box erecting machines to produce conventional Bliss-type H-divider containers have been available in the marketplace and used succesfully for several years. One of these is described in U.S. Pat. No. 4,220,076, to Moen. In this machine, an H-divider blank is formed into the H-divider and end wall portion at an upper location in the machine. This is then directed downward into a split mandrel. Here the H-divider is held within the mandrel while the end walls are positioned outside of but adjacent to the side walls of the mandrel. The body blank is then raised from below and formed about the mandrel. Both side walls of the container are bent upward against the mandrel faces normal to those supporting the end walls. After the side walls are in place, the end flaps, which are integral with the side walls and bottom, are folded into place and adhesively bonded to the end walls. The finished container is ejected from the mandrel by the next H-blank when it is introduced into the gap between the mandrel halves.
The inside-outside H-divider Bliss container is a very difficult box to form. To the present inventor's knowledge there is only one other machine available which can do this on a single-cycle basis. This has just very recently become available from SWF Machinery, Sanger, Calif. For this reason, containers of this type have had little availability in the marketplace despite their obvious attribute of superior top-to-bottom compression resistance.
The present invention enables an inside-outside Bliss-type container to be produced in a single-cycle operation on a Moen or similar type former.
A number of previous attempts have been made to modify a Moen or similar type machine to form an inside-outside Bliss-type construction. However, these have all been unsuccessful prior to the time of the present invention.